With the development of the large capability of magnetic storages and memory devices represented by magnetic disk devices (hard disks) or non-volatile random access magnetic memories (MRAM), use of a perpendicular magnetization film which is magnetized in a film perpendicular-to-plane direction as an information recording layer has been spotlighted. In addition, in order to improve a recording density of a hard disk and MRAM due to miniaturization of configuration recording bits of a hard disk recording medium or a tunnel magnetoresistance element (magnetic tunnel junction (MTJ) element) using the perpendicular magnetization, there is a need for a perpendicular magnetization material of which a magnetic anisotropy energy density Ku is high. In particular, for the MTJ element, it is required that saturation magnetization is small and a flat film structure is easily fabricated, in addition to the high Ku. The low saturation magnetization for the films is important to reduce modification of MTJ element characteristics or influence on adjacent elements due to leakage field from perpendicular magnetization film dots. Preparation of the flat film structure is important to reduce variation of each MTJ element having a multilayer film structure. In addition, when the perpendicular film is used as an information recording layer of the MTJ element for MRAM, reduction of power consumption for information writing using an electric current through the MTJ element (spin-transfer torque (STT) writing) is the major issue. For this purpose, it is required that a magnetic damping constant of the perpendicular magnetization film is small. Of cause, it is required that such a perpendicular magnetization film has a ferromagnetic transition temperature (Curie temperature) sufficiently higher than room temperature.
Until now, as the perpendicular magnetization film of the perpendicular magnetic recording medium, for example, Co-based alloy material, such as a cobalt-platinum-chrome (Co—Pt—Cr) alloy, has been known. Also, WO 2014/004398 A1 uses an L10 type iron-platinum (FePt) alloy from which a very high Ku is acquired. In K. Yakushiji, A. Fukushima, H. Kubota, M. Konoto, and S. Yuasa, “Ultralow-Voltage Spin-Transfer Switching in Perpendicularly Magnetized Magnetic Tunnel Junctions with Synthetic Antiferromagnetic Reference Layer,” Appl. Phys. Express, Vol. 6, No. 11, p 113006 (2013), as the MTJ element, a film acquired by alternately laminating Co atomic layers and Pt ones is used as a perpendicular magnetization film, which is a structure that applies a high Ku which a CoPt alloy has.
However, as described above, there are problems that existing perpendicular magnetization material contains an expensive noble metal, and magnetic damping is generally large. On the other hand, a manganese-gallium alloy of which magnetic damping is small without using a noble metal is a candidate of a perpendicular magnetization film (S. Mizukami, F. Wu, A. Sakuma, J. Walowski, D. Watanabe, T. Kubota, X. Zhang, H. Naganuma, M. Oogane, Y. Ando, and T. Miyazaki, “Long-Lived Ultrafast Spin Precession in Manganese Alloys Films with a Large Perpendicular Magnetic Anisotropy,” Phys. Rev. Lett., Vol. 106, No. 11, p. 117201 (2011)). However, since the manganese-gallium alloy material has a complex crystal structure belonging to a tetragonal crystal system, i.e. DO22 type or L10 type structure, a high formation temperature is required in order to obtain a film having a desired crystal structure. Therefore, there is a problem that it is hard to fabricate a flat film, and therefore, it is difficult to archive a high quality of a recording medium or MTJ element using the film.